Figure shows a bob of mass m suspended from a string of length L. The velocity is V 0 at A, then the potential energy of the system is at the lowest point A.

Question

Figure shows a bob of mass m suspended from a string of length L. The velocity is V 0 at A, then the potential energy of the system is at the lowest point A. (A) (1/2) m v02 (B) mgh (C) (-1/2) mv 02 (D) zero

Tardigrade Admin · Accepted Answer

At the lowest point, h =0 ∴ P.E. =0 (gravitational P.E.). There is no work done on the bob by the tension as it is perpendicular to the displacement. ∴ Potential energy is associated only to the gravitational force.

Q. Figure shows a bob of mass $m$ suspended from a string of length $L$ . The velocity is $V_{0}$ at $A$ , then the potential energy of the system is _______at the lowest point $A$ .

$\frac{1}{2} m v_{0}^{2}$

$m g h$

$\frac{- 1}{2} m v_{0}^{2}$

zero

At the lowest point, $h = 0$
$∴$ P.E. $= 0$ (gravitational P.E.). There is no work done on the bob by the tension as it is perpendicular to the displacement.
$∴$ Potential energy is associated only to the gravitational force.

Q. Figure shows a bob of mass m suspended from a string of length L. The velocity is V0​ at A, then the potential energy of the system is _______at the lowest point A.

21​mv02​

mgh

2−1​mv02​